Single RF oscillator technique for built-in tune, test, and calibration of a transceiver

ABSTRACT

Methods and various structures provide for loopback tuning, testing, and calibrating of a transceiver, including: supplying RF drive to both a transmitter and a receiver of the transceiver from one oscillator; applying a modulation waveform to a transceiver block of the transceiver to produce an amplitude-modulated signal; converting a sideband of the amplitude-modulated signal to a baseband signal having a frequency suitable for processing by a receiver digital block, where processing the baseband signal produces a digital output; and performing tuning, testing, and calibrating of the transceiver block, based at least in part on the digital output.

PRIORITY CLAIM

This application claims the benefit of Provisional Patent ApplicationNo. 62/187,629, filed Jul. 1, 2015, and Provisional Patent ApplicationNo. 62/190,168, filed Jul. 8, 2015, the contents of which are herebyincorporated by reference in their entirety.

BACKGROUND

A low cost transceiver utilizing frequency modulation in a simplex ortime-division duplex system may utilize a single precision oscillatorlocked to a high precision reference, for normal transmitter or receiveroperation. Since transmitter and receiver functions of the transceiverare not simultaneously active in this system, a single oscillator issufficient for normal operation.

System-on-Chip (SoC) transceivers implement on-chip tune, test andcalibration (TTC) circuitry to minimize the cost of external factoryequipment that would otherwise be necessary to perform these functions,and to enable these functions to be performed once transceivers are inuse in the field. A method used to perform TTC on various stages in thetransceiver is to inject a transmit path output into the receive pathinput, in a so called “loopback” topology, and then re-use receivedigital circuitry to perform signal analysis for the TTC. A requirementfor a periodic signal to be produced in the receive path and tested byreceive digital circuitry during the TTC function, however, cannot besatisfied if the same oscillator is used to directly and simultaneouslydrive both the transmit and receive paths. An additional and differentRF signal is therefore generated to drive the transmit path, exclusivelyfor TTC functions. This additional RF signal may be supplied by anadditional oscillator of the transceiver.

The requirement to create an additional high-quality RF signal is adesign burden; the additional oscillator required to generate the RFsignal adds silicon area (and, therefore, cost), and increases the peakpower required to supply the transceiver, due to the power drawn by theadditional oscillator and any additional circuitry associated with theoscillator, such as phase-locked loop circuits, during the TTCfunctions. That additional cost and peak power are associated with acircuit used only in TTC, and not while the transceiver is in normaloperation, makes it very desirable to find an alternative to the twooscillator approach.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings provide visual representations which will beused to more fully describe various representative embodiments and canbe used by those skilled in the art to better understand therepresentative embodiments disclosed and their inherent advantages. Inthese drawings, like reference numerals identify corresponding elements.

FIG. 1 is a block diagram that illustrates transmit mode of atransceiver, in accordance with various representative embodiments.

FIG. 2 is a block diagram that illustrates receive mode of atransceiver, in accordance with various representative embodiments.

FIG. 3 is a block diagram that illustrates loopback topology used toperform signal analysis during TTC, in accordance with the prior art.

FIG. 4 is a block diagram that illustrates loopback topology used toperform signal analysis during TTC, in accordance with variousrepresentative embodiments.

FIG. 5 is a flowchart that illustrates tuning of a transmit filter, inaccordance with various representative embodiments.

FIG. 6 is a flowchart that illustrates performing TTC of a transceiver,in accordance with various representative embodiments.

DETAILED DESCRIPTION

The various method, apparatus and devices described herein provide forTTC of a transceiver using one oscillator of the transceiver, therebyeliminating the need for a dedicated oscillator for TTC purposes.

In accordance with certain representative embodiments of the presentdisclosure, there is provided a method for TTC of a transceiver:supplying RF drive to both a transmitter and a receiver of thetransceiver from one oscillator; applying a modulation waveform to atransceiver block of the transceiver to produce an amplitude-modulatedsignal; converting a sideband of the amplitude-modulated signal to abaseband signal having a frequency suitable for processing by a receiverdigital block, where processing the baseband signal produces a digitaloutput; and performing at least one of tuning, testing, and calibratingof the transceiver block, based at least in part on the digital output.

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail specific embodiments, with the understanding that the presentdisclosure is to be considered as an example of the principles of theinvention and not intended to limit the invention to the specificembodiments shown and described. In the description below, likereference numerals are used to describe the same, similar orcorresponding parts in the several views of the drawings.

In this document, relational terms such as first and second, top andbottom, and the like may be used solely to distinguish one entity oraction from another entity or action without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element preceded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element.

Reference throughout this document to “one embodiment”, “certainembodiments”, “an embodiment” or similar terms means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the presentdisclosure. Thus, the appearances of such phrases or in various placesthroughout this specification are not necessarily all referring to thesame embodiment. Furthermore, the particular features, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments without limitation.

The term “or” as used herein is to be interpreted as an inclusive ormeaning any one or any combination. Therefore, “A, B or C” means “any ofthe following: A; B; C; A and B; A and C; B and C; A, B and C”. Anexception to this definition will occur only when a combination ofelements, functions, steps or acts are in some way inherently mutuallyexclusive.

For simplicity and clarity of illustration, reference numerals may berepeated among the figures to indicate corresponding or analogouselements. Numerous details are set forth to provide an understanding ofthe embodiments described herein. The embodiments may be practicedwithout these details. In other instances, well-known methods,procedures, and components have not been described in detail to avoidobscuring the embodiments described. The description is not to beconsidered as limited to the scope of the embodiments described herein.

Referring now to FIG. 1, as shown in diagram 100, when in transmit (TX)mode the voltage controlled oscillator (VCO) 114 of a phase-locked loop(PLL) is coupled to the input of a transmit buffer 120, supplying an RFdrive signal 116. PLL/frequency modulation block 110 applies the TXmodulating signal 112 directly to the VCO 114 as shown. The output ofthe transmit buffer 120 is coupled to the input of a transmit filter130. The output of the transmit filter 130 is coupled to the input of apower amplifier (PA) 140, and the output of the PA is coupled to the TXport of an antenna switch 150 as shown. In TX mode, the antenna switch150 couples the signal at its TX port to its antenna port. Receivefunctionality of the transceiver is denoted by the shaded blocks of thedrawing.

As shown in diagram 200 of FIG. 2, when in receive (RX) mode the VCO 114is coupled to the local oscillator (LO) input port of a receive mixer220, supplying an LO signal 210. For the function of the LO, thefrequency modulation function provided by frequency modulation block 110in the TX path is disabled and VCO 114 is kept locked to a multiple of aprecision reference. The RF input port of the mixer 220 is coupled tothe output 215 of a low-noise amplifier (LNA) 230 as shown. The input ofthe LNA 230 is coupled to the RX port of the antenna switch 240. In RXmode, the antenna switch 240 couples the signal at its antenna port toits RX port. An intermediate frequency (IF) output port of the mixer 220produces a mixer IF output signal 225 that is coupled to the input of anIF gain block 250. The output of the IF gain block 250 is coupled to theinput of a baseband filter 260. The output of the baseband filterproduces a baseband signal coupled to the RX digital block 270. Transmitfunctionality of the transceiver is denoted by the shaded blocks of thedrawing.

It can be seen that a transceiver (XCVR) in a simplex or time-divisionduplex (TDD) system utilizes a single precision oscillator, e.g., a VCOlocked to a high precision reference, for normal transmitter (TX) orReceiver (RX) operation. Since TX and RX functions of the transceiverare not simultaneously active in this system, a single oscillator (VCO114) is sufficient for normal operation.

System-on-Chip (SoC) XCVRs implement on-chip tune, test and calibration(TTC) circuitry to provide TTC to be performed on transceiver blocksalready in the field and at minimal cost. A method used to perform TTCon various stages in the XCVR is to inject a TX path output into the RXpath input, in a so called “loopback” topology, and then re-use the RXdigital circuitry to perform signal analysis for the TTC, as shown inthe transceiver block diagram 300 of FIG. 3.

A practical baseband signal to be analyzed by the RX digital circuitryis a periodic signal, such as a tone. This requirement for a periodicsignal to be produced in the RX path during the TTC function cannot besatisfied if the same oscillator is used to directly and simultaneouslydrive both the TX path (RF signal) and RX path (LO signal). To produce aperiodic baseband signal suitable for TTC purposes at the input to theRX digital block, an additional and different RF signal 310 must begenerated to drive the TX path, exclusively for the TTC functions. Inorder to produce the stable baseband signal of a desired frequencytypically required to perform these functions, this additional RF signal310 must be designed for high frequency accuracy, precision, andstability. Generally, this would be achieved with an additionaloscillator 320 controlled with a phase-locked loop coupled to aprecision reference available in the system. This requirement to createan additional high-quality RF signal is a design burden; the additionaloscillator 320 required to generate the high-quality RF signal 310 addssilicon area (and, therefore, cost), as well as increases the peak powerrequired to supply the XCVR 300, due to the power drawn by theadditional oscillator and any additional circuitry associated with theoscillator, such as phase-locked loop circuits, during the TTCfunctions. The fact that this additional cost and peak power resultsfrom a circuit used only in TTC, and not while the XCVR is in normaloperation, makes it very desirable to find an alternative, in whichloopback TTC of a XCVR is enabled without the requirement for anadditional oscillator.

As disclosed herein, the application of amplitude modulation to one ormore existing XCVR blocks is provided, enabling reuse of the transmitpath oscillator so that the need for a dedicated oscillator for TTCpurposes is eliminated. In an example embodiment shown in FIG. 4, thisis accomplished by using the same oscillator 114, locked to a precisionreference 430, to drive both the RX and TX paths, and by applying amodulation waveform 450 to the enable input of transmit buffer 120. ThusRX LO generation of LO signal 210 is unaffected, while the TX pathproduces an amplitude-modulated output 460 derived from the sameoscillator 114 as that used to drive the RX path. When applyingmodulation to the enable input of transmit buffer 120, the appliedmodulation waveform 450 provided by OOK control 410 will substantiallyenable and disable the TX signal 440 in accordance with the modulationwaveform generated by OOK control block 410 in response to the controlexerted by TTC controller 420. In this sense, TTC controller 420provides logic used control the flow of operation of the TX path duringa TTC mode. OOK control 410 controls the enable mode of TX buffer 120and picks a particular waveform to be applied. This approach may becontrasted with a more general TX system utilizing a vector modulator,for example, in which a substantially sinusoidal wave could be appliedto the modulator to accomplish the amplitude modulation. In accordancewith various embodiments herein, amplitude modulation may be produced bya modulating waveform that may be a series of pulses, a substantiallysquare wave, or a substantially sinusoidal wave, or other periodicbaseband signal, by way of example and not limitation.

The spectral location of the modulation sidebands of the TX output 440are defined by the frequency utilized to substantially enable anddisable, or ON-OFF Key (OOK) the TX output signal 440, via the enablecontrol signal 450 provided to the enable input of transmit buffer stage120. This control signal 450 provided by OOK control block 410 may be apulse with a programmable rate which can be precisely set from a highprecision digital clock (such as that derived from precision reference430 to phase lock the VCO 114 to a specific RF frequency), therebyproducing a TX signal with sidebands at precise, accurate, predictable,and controllable locations. In particular, sidebands may be placed suchthat, when the TX signal 440 is “looped back” into the RX path at LNA230, a sideband will be converted in frequency to a baseband frequencysuitable for processing by RX digital block 270, which produces adigital output 470. The digital output 470 contains the results ofprocessing of the baseband signal, and may include demodulation andamplitude determination processing results, by way of example and notlimitation.

In FIG. 4, oscillator (VCO 114) is an integral part of PLL/frequencymodulator 110. The frequency modulator 110 is fed by the transmit datastream 112, which applies instantaneous frequency deviation directly toVCO 114 during normal TX operation. VCO 114 is controlled by a phaselocked loop which is coupled to precision frequency reference 430 andkeeps the oscillator center frequency locked to a multiple of theprecision frequency reference. Oscillator 114 is coupled to bothtransmit buffer 120 input and the receiver mixer 220 LO port as shown.Transmit buffer 120 has its enable input driven by a modulation waveform450 received from OOK control block 410. OOK control block 410, in turn,is coupled to TTC controller 420. Additionally, OOK control block 410 iscoupled to the same precision frequency reference 430 that drives thephase locked loop of PLL/frequency modulator 110. Theamplitude-modulated output 460 of transmit buffer 120 is coupled to theinput of transmit filter 130. Transmit filter 130 has an adjustabletuning control input controlled by TTC controller 420 via OOK control410, e.g., the center frequency of the transmit filter 130 is adjustablein accordance with the control exerted by TTC controller 420 and OOKcontrol 410. The output of transmit filter 130 is coupled to PA 140, andthe PA output is coupled to the TX port of antenna switch 150. Inloopback mode, antenna switch 150 couples the signal at its TX port toits RX port, which is coupled to the input of LNA 230. The LNA output iscoupled to an RF input of receive mixer 220. An IF output port of mixer220 produces a mixer IF output signal 225 that is coupled to the inputof IF gain block 250. The output of IF gain block 250 is coupled to theinput of baseband filter 260. The output of baseband filter 260 producesa baseband signal 265 coupled to RX digital block 270. An output of RXdigital block 270 is coupled to TTC controller 420. TTC controller 420is also coupled to the PLL/frequency modulator 110 and directly controlsthe PLL setting of which oscillator (VCO 114) is a sub-block; TTCcontroller 420 is also a control input on antenna switch 150 asillustrated. Thus, TTC controller 420 commands the PLL to lock to aspecific frequency, and the loop action of the PLL controls the VCOfrequency.

By this technique a baseband signal 265 is generated with only a singleoscillator. The amplitude of the baseband signal may be analyzed by RXdigital block 270, and the result utilized to perform TTC on the XCVR400. In the loopback block diagram of FIG. 4, it is most beneficial tohave the modulated stage located close to the oscillator, so that themodulated signal is available to the maximum number of circuit blocksalong the loop that may need TTC; however, the modulation of otherblocks not so conveniently located is also contemplated.

Parameters of a transceiver block or transceiver component that may betuned, tested, or calibrated by the disclosed TTC method include filtercenter frequencies and bandwidths, block gains, maximum gain, relativepower changes (steps), among others. These parameters may be tuned,tested, or calibrated by adjusting any of a voltage, current,resistance, capacitance, and inductance associated with the circuitblock of interest. Thus, in accordance with various embodiments, tuning,testing and calibration may be accomplished in at least one or more ofthe following ways: adjusting a center frequency of a filter; adjustinga bandwidth of a filter; adjusting a gain of a block, which may includeadjusting a gain of a transceiver block for a target output level, suchas may be required of a PA driver block to produce a desired outputpower from a PA, or a receiver gain block to best trade sensitivity,blocking, and intermodulation performance; adjusting a gain of a blockin order to maximize its output level, as may be desired of an LNA tomaximize receiver sensitivity, or a PA to maximize output power;adjusting at least one of a voltage, current, resistance, capacitance,and inductance of a transceiver block, as may be done to maximize powerefficiency; adjusting a capacitor value in an interstageimpedance-matching circuit for a maximum output level of a transceiverblock (e.g., a matching stage between TX driver stages); determiningthat gain values of a switchable-gain block differ by predeterminedamounts, as may be done in PA driver blocks for applications requiringprecision PA output power; determining that the transceiver meetspredetermined specifications (for example, determining that the PAoutput power is within specification, or that the gain of an IF gainblock varies as required for Automatic Gain Control purposes); andidentifying a fault in at least one of the design and manufacture of thetransceiver (for example, identifying a design fault resulting in anunbiased LNA, or a tunable capacitor bank in the transmit filter havinga manufacturing defect resulting in substantially shifted ornon-existent resonance, both examples greatly attenuating the basebandsignal reaching the RX digital block during the loopback test).

A specific example for tuning a transmit filter is shown in the flowchart 500 of FIG. 5, in accordance with various disclosed embodimentsdisclosed herein. As indicated in FIG. 6, this flow is but one approachthat may be employed for performing TTC of a transceiver. Referring nowto FIG. 5, flow starts at block 510. At block 520, the TTC controllerplaces the XCVR into TTC loopback mode. This is accomplished by placingthe antenna switch in loopback mode (coupling the signal at its TX portto its RX port) and controlling the oscillator (VCO) to drive both thereceiver mixer and transmit buffer, thereby supplying RF drive to boththe TX and RX of the XCVR. At block 530, the TTC controller controls theOOK control block to supply a modulation waveform to the transmit bufferthat will produce a modulation sideband at the desired center frequencyof the filter. At block 540, the TTC controller evaluates the level ofthe baseband signal, as reported by the RF digital block. At block 550,the TTC controller adjusts the filter center frequency, e.g., byadjusting a value of a capacitor in the filter, for example, and thenre-evaluates the level of the baseband signal at block 560. As discussedabove, the TTC controller may perform TTC of the transceiver usingvarious other approaches, all of which are based at least in part on theRX digital output.

An overall flow of the embodiments disclosed herein is shown in FIG. 6.Flow starts at block 610. At block 620, RF drive is supplied to both TXand RX paths from one oscillator. Next, at block 630, a modulationwaveform is applied to a transceiver block, producing anamplitude-modulated signal. As described above, the modulation waveformapplied may be a series of pulses, a substantially square wave, and asubstantially sinusoidal wave, for example. At block 640, a sideband ofthe amplitude-modulated signal is converted to a baseband frequencysuitable for processing by a receiver digital block of the receiver,producing a digital output. At block 650, TTC is performed, meaning thatat least one of tuning, testing, and calibrating of a transceiver block(component) is performed, based at least in part on the RX digitaloutput.

Those skilled in the art will recognize that the present disclosure hasbeen described in terms of example embodiments based upon use of aprogrammed processor. However, the invention should not be so limited,since the present disclosure could be implemented using hardwarecomponent equivalents such as special purpose hardware and/or dedicatedprocessors which are equivalents to the invention as described andclaimed. Similarly, general purpose computers, microprocessor basedcomputers, micro-controllers, optical computers, analog computers,dedicated processors and/or dedicated hard wired logic may be used toconstruct alternative equivalent embodiments of the present disclosure.

Moreover, those skilled in the art will further appreciate that aprogram flow and associated data used to implement the embodimentsdescribed above can be implemented using various forms of storage suchas Read Only Memory (ROM), Random Access Memory (RAM), ElectricallyErasable Programmable Read Only Memory (EEPROM); non-volatile memory(NVM); mass storage such as a hard disc drive, floppy disc drive,optical disc drive; optical storage elements, magnetic storage elements,magneto-optical storage elements, flash memory, core memory and/or otherequivalent storage technologies without departing from the presentdisclosure. Such alternative storage devices should be consideredequivalents.

Various embodiments described herein are implemented using programmedprocessors executing programming instructions that are broadly describedin flow chart form that can be stored on any suitable electronic storagemedium or transmitted over any suitable electronic communication medium.However, those skilled in the art will appreciate that the processesdescribed above can be implemented in any number of variations and inmany suitable programming languages without departing from the presentdisclosure. For example, the order of certain operations carried out canoften be varied, additional operations can be added or operations can bedeleted without departing from the disclosure. Error trapping can beadded and/or enhanced and variations can be made in user interface andinformation presentation without departing from the present disclosure.Such variations are contemplated and considered equivalent.

The representative embodiments, which have been described in detailherein, have been presented by way of example and not by way oflimitation. It will be understood by those skilled in the art thatvarious changes may be made in the form and details of the describedembodiments resulting in equivalent embodiments that remain within thescope of the appended claims.

Accordingly, some features of the disclosed embodiments are set out inthe following numbered items:

-   1. A method for loopback tuning, testing, and calibrating (TTC) of a    transceiver, comprising:    -   supplying RF drive to both a transmitter and a receiver of the        transceiver from one oscillator;    -   applying a modulation waveform to a transceiver block of the        transceiver to produce an amplitude-modulated signal;    -   converting a sideband of the amplitude-modulated signal to a        baseband signal having a frequency suitable for processing by a        receiver digital block, where processing the baseband signal        produces a digital output; and    -   performing at least one of tuning, testing, and calibrating of        the transceiver block, based at least in part on the digital        output.-   2. The method of item 1, further comprising:-   prior to supplying RF drive:    -   a TTC controller setting the transceiver into a TTC mode; and-   prior to applying the modulation waveform:    -   the TTC controller controlling a controller to supply the        modulation waveform.-   3. The method of item 2, where setting the transceiver into the TTC    mode comprises:    -   placing an antenna switch of the transceiver in loopback mode by        coupling a signal at a transmitter (TX) port of the antenna        switch to a receiver (RX) port of the antenna switch; and    -   controlling the one oscillator to drive both a receiver mixer        and a transmit buffer of the transceiver; and-   where the TTC controller controlling a controller to supply a    modulation waveform comprises:    -   controlling an OOK control block to supply the modulation        waveform to the transmit buffer to produce a modulation sideband        at a desired center frequency of a transmit filter.-   4. The method of item 2, further comprising:    -   the TTC controller adjusting a center frequency of a transmit        filter; and    -   re-evaluating the adjusted baseband signal.-   5. The method of item 1, where applying the modulation waveform to a    transceiver block comprises applying the modulation waveform to an    enable input of the transceiver block.-   6. The method of item 1, where the modulation waveform is a series    of pulses.-   7. The method of item 1, where the modulation waveform is a    substantially square wave.-   8. The method of item 1, where the modulation waveform is a    substantially sinusoidal wave.-   9. The method of item 1, where performing the at least one of    tuning, testing, and calibrating comprises adjusting a center    frequency of a filter.-   10. The method of item 1, where performing the at least one of    tuning, testing, and calibrating comprises adjusting a bandwidth of    a filter.-   11. The method of item 1, where the at least one of tuning, testing,    and calibrating comprises adjusting a gain of the transceiver block.-   12. The method of item 11, where the adjusting the gain of the    transceiver block comprises adjusting at least one of a voltage,    current, resistance, capacitance, and inductance of the transceiver    block.-   13. The method of item 11, where adjusting the gain of the    transceiver block is performed for a target output level.-   14. The method of item 1, where the at least one of tuning, testing,    and calibrating comprises adjusting a capacitor value for a maximum    output level of the transceiver block.-   15. The method of item 1, where the at least one of tuning, testing,    and calibrating comprises determining that gain values of a    switchable-gain block differ by predetermined amounts.-   16. The method of item 1, where the at least one of tuning, testing,    and calibrating comprises determining that the transceiver meets    predetermined specifications.-   17. The method of item 1, where the at least one of tuning, testing,    and calibrating comprises identifying a fault in at least one of the    design and manufacture of the transceiver.-   18. The method of item 1, where the one oscillator is a voltage    controlled oscillator.-   19. The method of item 1, where the transmitter of the transceiver    is frequency modulated.

What is claimed is:
 1. A method for loopback tuning, testing, andcalibrating (TTC) of a transceiver, comprising: supplying RF drive toboth a transmitter and a receiver of the transceiver from oneoscillator; applying a modulation waveform to a transceiver block of thetransceiver to produce an amplitude-modulated signal; converting asideband of the amplitude-modulated signal to a baseband signal having afrequency suitable for processing by a receiver digital block, whereprocessing the baseband signal produces a digital output; and performingat least one of tuning, testing, and calibrating of the transceiverblock, based at least in part on the digital output.
 2. The method ofclaim 1, further comprising: prior to supplying RF drive: a TTCcontroller setting the transceiver into a TTC mode; and prior toapplying the modulation waveform: the TTC controller controlling acontroller to supply the modulation waveform.
 3. The method of claim 2,where setting the transceiver into the TTC mode comprises: placing anantenna switch of the transceiver in loopback mode by coupling a signalat a transmitter (TX) port of the antenna switch to a receiver (RX) portof the antenna switch; and controlling the one oscillator to drive botha receiver mixer and a transmit buffer of the transceiver; and where theTTC controller controlling a controller to supply a modulation waveformcomprises: controlling an On-Off Key (OOK) control block to supply themodulation waveform to the transmit buffer to produce a modulationsideband at a desired center frequency of a transmit filter.
 4. Themethod of claim 2, further comprising: the TTC controller adjusting acenter frequency of a transmit filter to produce an adjusted basebandsignal; and re-evaluating the adjusted baseband signal.
 5. The method ofclaim 1, where applying the modulation waveform to a transceiver blockcomprises applying the modulation waveform to an enable input of thetransceiver block.
 6. The method of claim 1, where the modulationwaveform is a series of pulses.
 7. The method of claim 1, where themodulation waveform is a substantially square wave.
 8. The method ofclaim 1, where the modulation waveform is a substantially sinusoidalwave.
 9. The method of claim 1, where performing the at least one oftuning, testing, and calibrating comprises adjusting a center frequencyof a filter.
 10. The method of claim 1, where performing the at leastone of tuning, testing, and calibrating comprises adjusting a bandwidthof a filter.
 11. The method of claim 1, where the at least one oftuning, testing, and calibrating comprises adjusting a gain of thetransceiver block.
 12. The method of claim 11, where the adjusting thegain of the transceiver block comprises adjusting at least one of avoltage, current, resistance, capacitance, and inductance of thetransceiver block.
 13. The method of claim 11, where adjusting the gainof the transceiver block is performed for a target output level.
 14. Themethod of claim 1, where the at least one of tuning, testing, andcalibrating comprises adjusting a capacitor value for a maximum outputlevel of the transceiver block.
 15. The method of claim 1, where the atleast one of tuning, testing, and calibrating comprises determining thatgain values of a switchable-gain block differ by predetermined amounts.16. The method of claim 1, where the at least one of tuning, testing,and calibrating comprises determining that the transceiver meetspredetermined specifications.
 17. The method of claim 1, where the atleast one of tuning, testing, and calibrating comprises identifying afault in at least one of design and manufacture of the transceiver. 18.The method of claim 1, where the one oscillator is a voltage controlledoscillator.
 19. The method of claim 1, where the transmitter of thetransceiver is frequency modulated.